1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_SHARED_COLLECTEDHEAP_HPP
  26 #define SHARE_GC_SHARED_COLLECTEDHEAP_HPP
  27 
  28 #include "gc/shared/gcCause.hpp"
  29 #include "gc/shared/gcWhen.hpp"
  30 #include "gc/shared/objectMarker.hpp"
  31 #include "gc/shared/verifyOption.hpp"
  32 #include "memory/allocation.hpp"
  33 #include "runtime/handles.hpp"
  34 #include "runtime/perfData.hpp"
  35 #include "runtime/safepoint.hpp"
  36 #include "services/memoryUsage.hpp"
  37 #include "utilities/debug.hpp"
  38 #include "utilities/events.hpp"
  39 #include "utilities/formatBuffer.hpp"
  40 #include "utilities/growableArray.hpp"
  41 
  42 // A "CollectedHeap" is an implementation of a java heap for HotSpot.  This
  43 // is an abstract class: there may be many different kinds of heaps.  This
  44 // class defines the functions that a heap must implement, and contains
  45 // infrastructure common to all heaps.
  46 
  47 class AdaptiveSizePolicy;
  48 class BarrierSet;
  49 class GCHeapSummary;
  50 class GCTimer;
  51 class GCTracer;
  52 class GCMemoryManager;
  53 class MemoryPool;
  54 class MetaspaceSummary;
  55 class ReservedHeapSpace;
  56 class SoftRefPolicy;
  57 class Thread;
  58 class ThreadClosure;
  59 class VirtualSpaceSummary;
  60 class WorkGang;
  61 class nmethod;
  62 
  63 class GCMessage : public FormatBuffer<1024> {
  64  public:
  65   bool is_before;
  66 
  67  public:
  68   GCMessage() {}
  69 };
  70 
  71 class CollectedHeap;
  72 
  73 class GCHeapLog : public EventLogBase<GCMessage> {
  74  private:
  75   void log_heap(CollectedHeap* heap, bool before);
  76 
  77  public:
  78   GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
  79 
  80   void log_heap_before(CollectedHeap* heap) {
  81     log_heap(heap, true);
  82   }
  83   void log_heap_after(CollectedHeap* heap) {
  84     log_heap(heap, false);
  85   }
  86 };
  87 
  88 //
  89 // CollectedHeap
  90 //   GenCollectedHeap
  91 //     SerialHeap
  92 //   G1CollectedHeap
  93 //   ParallelScavengeHeap
  94 //   ShenandoahHeap
  95 //   ZCollectedHeap
  96 //
  97 class CollectedHeap : public CHeapObj<mtInternal> {
  98   friend class VMStructs;
  99   friend class JVMCIVMStructs;
 100   friend class IsGCActiveMark; // Block structured external access to _is_gc_active
 101   friend class MemAllocator;
 102 
 103  private:
 104   GCHeapLog* _gc_heap_log;
 105 
 106  protected:
 107   // Not used by all GCs
 108   MemRegion _reserved;
 109 
 110   bool _is_gc_active;
 111 
 112   // Used for filler objects (static, but initialized in ctor).
 113   static size_t _filler_array_max_size;
 114 
 115   unsigned int _total_collections;          // ... started
 116   unsigned int _total_full_collections;     // ... started
 117   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
 118   NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
 119 
 120   // Reason for current garbage collection.  Should be set to
 121   // a value reflecting no collection between collections.
 122   GCCause::Cause _gc_cause;
 123   GCCause::Cause _gc_lastcause;
 124   PerfStringVariable* _perf_gc_cause;
 125   PerfStringVariable* _perf_gc_lastcause;
 126 
 127   // Constructor
 128   CollectedHeap();
 129 
 130   // Create a new tlab. All TLAB allocations must go through this.
 131   // To allow more flexible TLAB allocations min_size specifies
 132   // the minimum size needed, while requested_size is the requested
 133   // size based on ergonomics. The actually allocated size will be
 134   // returned in actual_size.
 135   virtual HeapWord* allocate_new_tlab(size_t min_size,
 136                                       size_t requested_size,
 137                                       size_t* actual_size);
 138 
 139   // Reinitialize tlabs before resuming mutators.
 140   virtual void resize_all_tlabs();
 141 
 142   // Raw memory allocation facilities
 143   // The obj and array allocate methods are covers for these methods.
 144   // mem_allocate() should never be
 145   // called to allocate TLABs, only individual objects.
 146   virtual HeapWord* mem_allocate(size_t size,
 147                                  bool* gc_overhead_limit_was_exceeded) = 0;
 148 
 149   // Filler object utilities.
 150   static inline size_t filler_array_hdr_size();
 151   static inline size_t filler_array_min_size();
 152 
 153   DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
 154   DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
 155 
 156   // Fill with a single array; caller must ensure filler_array_min_size() <=
 157   // words <= filler_array_max_size().
 158   static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
 159 
 160   // Fill with a single object (either an int array or a java.lang.Object).
 161   static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
 162 
 163   virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 164 
 165   // Verification functions
 166   virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
 167     PRODUCT_RETURN;
 168   debug_only(static void check_for_valid_allocation_state();)
 169 
 170  public:
 171   enum Name {
 172     None,
 173     Serial,
 174     Parallel,
 175     G1,
 176     Epsilon,
 177     Z,
 178     Shenandoah
 179   };
 180 
 181   static inline size_t filler_array_max_size() {
 182     return _filler_array_max_size;
 183   }
 184 
 185   virtual Name kind() const = 0;
 186 
 187   virtual const char* name() const = 0;
 188 
 189   /**
 190    * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
 191    * and JNI_OK on success.
 192    */
 193   virtual jint initialize() = 0;
 194 
 195   // In many heaps, there will be a need to perform some initialization activities
 196   // after the Universe is fully formed, but before general heap allocation is allowed.
 197   // This is the correct place to place such initialization methods.
 198   virtual void post_initialize();
 199 
 200   // Stop any onging concurrent work and prepare for exit.
 201   virtual void stop() {}
 202 
 203   // Stop and resume concurrent GC threads interfering with safepoint operations
 204   virtual void safepoint_synchronize_begin() {}
 205   virtual void safepoint_synchronize_end() {}
 206 
 207   void initialize_reserved_region(const ReservedHeapSpace& rs);
 208 
 209   virtual size_t capacity() const = 0;
 210   virtual size_t used() const = 0;
 211 
 212   // Returns unused capacity.
 213   virtual size_t unused() const;
 214 
 215   // Return "true" if the part of the heap that allocates Java
 216   // objects has reached the maximal committed limit that it can
 217   // reach, without a garbage collection.
 218   virtual bool is_maximal_no_gc() const = 0;
 219 
 220   // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
 221   // memory that the vm could make available for storing 'normal' java objects.
 222   // This is based on the reserved address space, but should not include space
 223   // that the vm uses internally for bookkeeping or temporary storage
 224   // (e.g., in the case of the young gen, one of the survivor
 225   // spaces).
 226   virtual size_t max_capacity() const = 0;
 227 
 228   // Returns "TRUE" iff "p" points into the committed areas of the heap.
 229   // This method can be expensive so avoid using it in performance critical
 230   // code.
 231   virtual bool is_in(const void* p) const = 0;
 232 
 233   DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
 234 
 235   virtual uint32_t hash_oop(oop obj) const;
 236 
 237   void set_gc_cause(GCCause::Cause v) {
 238      if (UsePerfData) {
 239        _gc_lastcause = _gc_cause;
 240        _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
 241        _perf_gc_cause->set_value(GCCause::to_string(v));
 242      }
 243     _gc_cause = v;
 244   }
 245   GCCause::Cause gc_cause() { return _gc_cause; }
 246 
 247   oop obj_allocate(Klass* klass, int size, TRAPS);
 248   virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
 249   oop class_allocate(Klass* klass, int size, TRAPS);
 250 
 251   // Utilities for turning raw memory into filler objects.
 252   //
 253   // min_fill_size() is the smallest region that can be filled.
 254   // fill_with_objects() can fill arbitrary-sized regions of the heap using
 255   // multiple objects.  fill_with_object() is for regions known to be smaller
 256   // than the largest array of integers; it uses a single object to fill the
 257   // region and has slightly less overhead.
 258   static size_t min_fill_size() {
 259     return size_t(align_object_size(oopDesc::header_size()));
 260   }
 261 
 262   static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
 263 
 264   static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
 265   static void fill_with_object(MemRegion region, bool zap = true) {
 266     fill_with_object(region.start(), region.word_size(), zap);
 267   }
 268   static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
 269     fill_with_object(start, pointer_delta(end, start), zap);
 270   }
 271 
 272   virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
 273   virtual size_t min_dummy_object_size() const;
 274   size_t tlab_alloc_reserve() const;
 275 
 276   // Return the address "addr" aligned by "alignment_in_bytes" if such
 277   // an address is below "end".  Return NULL otherwise.
 278   inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
 279                                                    HeapWord* end,
 280                                                    unsigned short alignment_in_bytes);
 281 
 282   // Some heaps may offer a contiguous region for shared non-blocking
 283   // allocation, via inlined code (by exporting the address of the top and
 284   // end fields defining the extent of the contiguous allocation region.)
 285 
 286   // This function returns "true" iff the heap supports this kind of
 287   // allocation.  (Default is "no".)
 288   virtual bool supports_inline_contig_alloc() const {
 289     return false;
 290   }
 291   // These functions return the addresses of the fields that define the
 292   // boundaries of the contiguous allocation area.  (These fields should be
 293   // physically near to one another.)
 294   virtual HeapWord* volatile* top_addr() const {
 295     guarantee(false, "inline contiguous allocation not supported");
 296     return NULL;
 297   }
 298   virtual HeapWord** end_addr() const {
 299     guarantee(false, "inline contiguous allocation not supported");
 300     return NULL;
 301   }
 302 
 303   // Some heaps may be in an unparseable state at certain times between
 304   // collections. This may be necessary for efficient implementation of
 305   // certain allocation-related activities. Calling this function before
 306   // attempting to parse a heap ensures that the heap is in a parsable
 307   // state (provided other concurrent activity does not introduce
 308   // unparsability). It is normally expected, therefore, that this
 309   // method is invoked with the world stopped.
 310   // NOTE: if you override this method, make sure you call
 311   // super::ensure_parsability so that the non-generational
 312   // part of the work gets done. See implementation of
 313   // CollectedHeap::ensure_parsability and, for instance,
 314   // that of GenCollectedHeap::ensure_parsability().
 315   // The argument "retire_tlabs" controls whether existing TLABs
 316   // are merely filled or also retired, thus preventing further
 317   // allocation from them and necessitating allocation of new TLABs.
 318   virtual void ensure_parsability(bool retire_tlabs);
 319 
 320   // Section on thread-local allocation buffers (TLABs)
 321   // If the heap supports thread-local allocation buffers, it should override
 322   // the following methods:
 323   // Returns "true" iff the heap supports thread-local allocation buffers.
 324   // The default is "no".
 325   virtual bool supports_tlab_allocation() const = 0;
 326 
 327   // The amount of space available for thread-local allocation buffers.
 328   virtual size_t tlab_capacity(Thread *thr) const = 0;
 329 
 330   // The amount of used space for thread-local allocation buffers for the given thread.
 331   virtual size_t tlab_used(Thread *thr) const = 0;
 332 
 333   virtual size_t max_tlab_size() const;
 334 
 335   // An estimate of the maximum allocation that could be performed
 336   // for thread-local allocation buffers without triggering any
 337   // collection or expansion activity.
 338   virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
 339     guarantee(false, "thread-local allocation buffers not supported");
 340     return 0;
 341   }
 342 
 343   // Perform a collection of the heap; intended for use in implementing
 344   // "System.gc".  This probably implies as full a collection as the
 345   // "CollectedHeap" supports.
 346   virtual void collect(GCCause::Cause cause) = 0;
 347 
 348   // Perform a full collection
 349   virtual void do_full_collection(bool clear_all_soft_refs) = 0;
 350 
 351   // This interface assumes that it's being called by the
 352   // vm thread. It collects the heap assuming that the
 353   // heap lock is already held and that we are executing in
 354   // the context of the vm thread.
 355   virtual void collect_as_vm_thread(GCCause::Cause cause);
 356 
 357   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 358                                                        size_t size,
 359                                                        Metaspace::MetadataType mdtype);
 360 
 361   // Returns "true" iff there is a stop-world GC in progress.  (I assume
 362   // that it should answer "false" for the concurrent part of a concurrent
 363   // collector -- dld).
 364   bool is_gc_active() const { return _is_gc_active; }
 365 
 366   // Total number of GC collections (started)
 367   unsigned int total_collections() const { return _total_collections; }
 368   unsigned int total_full_collections() const { return _total_full_collections;}
 369 
 370   // Increment total number of GC collections (started)
 371   void increment_total_collections(bool full = false) {
 372     _total_collections++;
 373     if (full) {
 374       increment_total_full_collections();
 375     }
 376   }
 377 
 378   void increment_total_full_collections() { _total_full_collections++; }
 379 
 380   // Return the SoftRefPolicy for the heap;
 381   virtual SoftRefPolicy* soft_ref_policy() = 0;
 382 
 383   virtual MemoryUsage memory_usage();
 384   virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
 385   virtual GrowableArray<MemoryPool*> memory_pools() = 0;
 386 
 387   // ObjectMarker for JVMTI heap walk
 388   virtual ObjectMarker* object_marker();
 389 
 390   // Iterate over all objects, calling "cl.do_object" on each.
 391   virtual void object_iterate(ObjectClosure* cl) = 0;
 392 
 393   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
 394   virtual void keep_alive(oop obj) {}
 395 
 396   // Returns the longest time (in ms) that has elapsed since the last
 397   // time that any part of the heap was examined by a garbage collection.
 398   virtual jlong millis_since_last_gc() = 0;
 399 
 400   // Perform any cleanup actions necessary before allowing a verification.
 401   virtual void prepare_for_verify() = 0;
 402 
 403   // Generate any dumps preceding or following a full gc
 404  private:
 405   void full_gc_dump(GCTimer* timer, bool before);
 406 
 407   virtual void initialize_serviceability() = 0;
 408 
 409  public:
 410   void pre_full_gc_dump(GCTimer* timer);
 411   void post_full_gc_dump(GCTimer* timer);
 412 
 413   virtual VirtualSpaceSummary create_heap_space_summary();
 414   GCHeapSummary create_heap_summary();
 415 
 416   MetaspaceSummary create_metaspace_summary();
 417 
 418   // Print heap information on the given outputStream.
 419   virtual void print_on(outputStream* st) const = 0;
 420   // The default behavior is to call print_on() on tty.
 421   virtual void print() const;
 422 
 423   // Print more detailed heap information on the given
 424   // outputStream. The default behavior is to call print_on(). It is
 425   // up to each subclass to override it and add any additional output
 426   // it needs.
 427   virtual void print_extended_on(outputStream* st) const {
 428     print_on(st);
 429   }
 430 
 431   virtual void print_on_error(outputStream* st) const;
 432 
 433   // Used to print information about locations in the hs_err file.
 434   virtual bool print_location(outputStream* st, void* addr) const = 0;
 435 
 436   // Print all GC threads (other than the VM thread)
 437   // used by this heap.
 438   virtual void print_gc_threads_on(outputStream* st) const = 0;
 439   // The default behavior is to call print_gc_threads_on() on tty.
 440   void print_gc_threads() {
 441     print_gc_threads_on(tty);
 442   }
 443   // Iterator for all GC threads (other than VM thread)
 444   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
 445 
 446   // Print any relevant tracing info that flags imply.
 447   // Default implementation does nothing.
 448   virtual void print_tracing_info() const = 0;
 449 
 450   void print_heap_before_gc();
 451   void print_heap_after_gc();
 452 
 453   // Registering and unregistering an nmethod (compiled code) with the heap.
 454   virtual void register_nmethod(nmethod* nm) = 0;
 455   virtual void unregister_nmethod(nmethod* nm) = 0;
 456   // Callback for when nmethod is about to be deleted.
 457   virtual void flush_nmethod(nmethod* nm) = 0;
 458   virtual void verify_nmethod(nmethod* nm) = 0;
 459 
 460   void trace_heap_before_gc(const GCTracer* gc_tracer);
 461   void trace_heap_after_gc(const GCTracer* gc_tracer);
 462 
 463   // Heap verification
 464   virtual void verify(VerifyOption option) = 0;
 465 
 466   // Return true if concurrent phase control (via
 467   // request_concurrent_phase_control) is supported by this collector.
 468   // The default implementation returns false.
 469   virtual bool supports_concurrent_phase_control() const;
 470 
 471   // Request the collector enter the indicated concurrent phase, and
 472   // wait until it does so.  Supports WhiteBox testing.  Only one
 473   // request may be active at a time.  Phases are designated by name;
 474   // the set of names and their meaning is GC-specific.  Once the
 475   // requested phase has been reached, the collector will attempt to
 476   // avoid transitioning to a new phase until a new request is made.
 477   // [Note: A collector might not be able to remain in a given phase.
 478   // For example, a full collection might cancel an in-progress
 479   // concurrent collection.]
 480   //
 481   // Returns true when the phase is reached.  Returns false for an
 482   // unknown phase.  The default implementation returns false.
 483   virtual bool request_concurrent_phase(const char* phase);
 484 
 485   // Provides a thread pool to SafepointSynchronize to use
 486   // for parallel safepoint cleanup.
 487   // GCs that use a GC worker thread pool may want to share
 488   // it for use during safepoint cleanup. This is only possible
 489   // if the GC can pause and resume concurrent work (e.g. G1
 490   // concurrent marking) for an intermittent non-GC safepoint.
 491   // If this method returns NULL, SafepointSynchronize will
 492   // perform cleanup tasks serially in the VMThread.
 493   virtual WorkGang* get_safepoint_workers() { return NULL; }
 494 
 495   // Support for object pinning. This is used by JNI Get*Critical()
 496   // and Release*Critical() family of functions. If supported, the GC
 497   // must guarantee that pinned objects never move.
 498   virtual bool supports_object_pinning() const;
 499   virtual oop pin_object(JavaThread* thread, oop obj);
 500   virtual void unpin_object(JavaThread* thread, oop obj);
 501 
 502   // Deduplicate the string, iff the GC supports string deduplication.
 503   virtual void deduplicate_string(oop str);
 504 
 505   virtual bool is_oop(oop object) const;
 506 
 507   virtual size_t obj_size(oop obj) const;
 508 
 509   // Non product verification and debugging.
 510 #ifndef PRODUCT
 511   // Support for PromotionFailureALot.  Return true if it's time to cause a
 512   // promotion failure.  The no-argument version uses
 513   // this->_promotion_failure_alot_count as the counter.
 514   bool promotion_should_fail(volatile size_t* count);
 515   bool promotion_should_fail();
 516 
 517   // Reset the PromotionFailureALot counters.  Should be called at the end of a
 518   // GC in which promotion failure occurred.
 519   void reset_promotion_should_fail(volatile size_t* count);
 520   void reset_promotion_should_fail();
 521 #endif  // #ifndef PRODUCT
 522 };
 523 
 524 // Class to set and reset the GC cause for a CollectedHeap.
 525 
 526 class GCCauseSetter : StackObj {
 527   CollectedHeap* _heap;
 528   GCCause::Cause _previous_cause;
 529  public:
 530   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
 531     _heap = heap;
 532     _previous_cause = _heap->gc_cause();
 533     _heap->set_gc_cause(cause);
 534   }
 535 
 536   ~GCCauseSetter() {
 537     _heap->set_gc_cause(_previous_cause);
 538   }
 539 };
 540 
 541 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP
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